Se o motorista estiver cansado, é melhor não pegar o volante.

to be

Breakdown of Se o motorista estiver cansado, é melhor não pegar o volante.

• estar: to be
• cansado: tired
• não: not

Questions & Answers about Se o motorista estiver cansado, é melhor não pegar o volante.

Why is estiver used instead of está?

Because after se when you are talking about a possible future situation, Portuguese often uses the future subjunctive.

• Se o motorista está cansado... = if the driver is tired (more like describing a present fact)
• Se o motorista estiver cansado... = if the driver is tired / if the driver happens to be tired

In this sentence, the idea is conditional and forward-looking: in the event that the driver is tired. That is why estiver is the natural choice.

The verb here is estar, and estiver is the future subjunctive form for ele/ela/você.

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What exactly does se mean here?

Here, se means if.

It introduces a condition:

• Se o motorista estiver cansado... = If the driver is tired...

This is one of the most common uses of se in Portuguese.

Be careful, because se can also mean other things in other contexts, such as a reflexive pronoun, but here it is simply if.

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Why does the sentence use o motorista? Does it mean a specific driver or drivers in general?